From the back cover

The Greatest Heroes of Two Worlds... Together at Last!

When the deadliest villains of two universes - Dr. Destroyer and Kreutzritter - team up to threaten both realities with their evil schemes, it's up to the heroes of both worlds - the Guard and the Champions - to join forces and stop them... but they need your heroes' help if they're going to succeed! Reality Storm presents this pulse-pounding superhero adventure for two game systems - Champions and Silver Age Sentinels - with enough action and adventure to satisfy any campaign!

Reality Storm includes:

Silver Age Sentinels stats for the Champions and Champions Universe villains, and Hero System stats for the Guard and the villains of Empire City

complete, official conversion rules for translating Champions characters into Silver Age Sentinels terms, and vice-versa!